How closures capture variables

Closures capture variables from their surrounding scope by borrowing or taking ownership of them when they are defined. The compiler infers whether to borrow immutably, mutably, or move the value based on how the closure uses it, storing the captured data within the closure's environment. Use the move keyword to force the closure to take ownership of all captured variables immediately.

let x = 5;
let capture_borrow = || println!("x: {}", x);
let capture_move = move || println!("x: {}", x);

A closure is a small piece of code that can remember variables from the place where it was created. It works like a backpack that packs up the items it needs from its surroundings so it can use them later, even after the original context is gone. You use this feature to create flexible functions that carry their own data without needing to pass it as arguments every time.